What Is an Electricity Meter? Energy Meter Selection Guide
An electricity meter measures and totals the electrical energy passing through a circuit in kWh; this guide covers connection current, communication, tariff and accuracy class.
What is an electricity meter and where is it used
An electricity meter is a device that measures and totals the electrical energy passing through a circuit over a given time in kilowatt-hours (kWh); in everyday language it is also called a kWh meter or energy meter. The products in this category are Schneider Electric models described in their product names as "direct-connected 3-phase kWh meter". They are used as sub-meters to monitor consumption separately by line, panel or load. This category covers not the subscriber meter installed by the electricity distribution company, but these sub-meters used to monitor consumption within the facility.
In the manufacturer data, multi-tariff, sub-billing and partial counter are stated as applications for a model in this class (iEM3155). Whether a meter is suitable for billing or regulatory use must be confirmed separately according to the project specification and the requirements of the relevant authority.
Types of electricity meters
The products in the category are the Schneider Electric iEM3000 series, and the following distinctions appear in the product names:
- Connection current: Direct-connected three-phase kWh meters in the 63 A and 125 A classes.
- Communication: Modbus, BACnet or pulse output. Modbus and BACnet transfer data to an energy monitoring system; the pulse output sends an energy pulse to a PLC or counter.
- Tariff: Models with multi-tariff support record consumption in different time periods separately.
- MID: Some product names carry the MID mark.
The models in this category are direct-connected. If the line current exceeds the limit of these models, the measurement is set up through a current transformer; for the transformer side, see the current transformers page.
What to look at when choosing an electricity meter
- Connection type and current: The load current of the line must stay within the direct measurement current limits given in the product data. For a preliminary estimate of the load current, you can use the current calculation from active power tool; the final decision is made according to the project and the manufacturer data.
- Network configuration: The iEM3155 manufacturer data lists three-phase with neutral (3P+N), single-phase with neutral (1P+N) and three-phase (3P) networks; verify on the product page of the model you choose that it matches your line.
- Accuracy class and standard: The iEM3155 manufacturer data states Class 1 for active energy according to IEC 62053-21 and IEC 61557-12, and Class B according to EN 50470-3. For other models, check the class and the referenced standard on the product page.
- Communication: Look at the protocol of your existing monitoring system. For the iEM3155, the manufacturer data states Modbus RTU and an RS485 screw terminal; on the cable side, RS-485 cables and, if needed, energy monitoring software are planned together.
- Tariff: If you need consumption separated by time period, look for multi-tariff support.
- Mounting and dimensions: Width is given in 9 mm module pitches and varies by model; the iEM3155 manufacturer data states clip-on DIN rail mounting and 10 module pitches. Plan the enclosure layout according to the dimensions on the product page of the model you choose.
Installation and commissioning are carried out by an authorized electrician according to the project and the manufacturer data.
The difference between an electricity meter and a power network analyzer
The main job of a meter is to record the energy total (kWh); in the iEM3155 manufacturer data, current, voltage and power are also listed among the measurement types. Power network analyzers, on the other hand, are a separate product group for examining power quality. If you only want to allocate consumption, a meter is more suitable; if you want to examine network quality, power network analyzers are, and to read instantaneous values on the panel, panel-mount multimeters are. Hour meters, which count the machine's operating time, do not measure energy.
Brands in this category
Currently Schneider Electric products are listed in the category. The 63 A models are named iEM3110 (with pulse output), iEM3115 (multi-tariff), iEM3150 (Modbus), iEM3155 (Modbus, MID) and iEM3165 (BACnet, MID); the 125 A models are named iEM3350 (Modbus), iEM3355 (Modbus, MID) and iEM3365 (BACnet, MID). For other devices in the same parent category, see the Measuring and Control Devices page.
Ordering notes
Products are listed by the piece, and all products in the category are marked as made to order (terminli); for these products, the delivery time is confirmed at the time of the order. You can search for the model you want by stock code, such as A9MEM3155.
Comparison and selection table
| Selection Criterion | Single-Phase Direct Energy Meter | Three-Phase Direct Energy Meter | Three-Phase CT-Operated (X/5 A) Combi Meter |
|---|---|---|---|
| Connection & Current | 1P 230 V, 5(60) A – 10(100) A direct | 3P 400 V, 5(80) A – 10(100) A direct | Via X/5 A current transformers (>100 A feeders) |
| Measured Quantities | Active energy (kWh), single or multi-tariff | Active (kWh) or Active + Reactive (Combi) | Active (kWh) + Inductive/Capacitive Reactive (kVArh) |
| Mounting & Comms | DIN rail (1–2 modules) or panel mount, RS485 | DIN rail (4–7 modules) or 3-point wall mount | Panel/wall mount, optical port + RS485 Modbus |
| Typical Application | Apartments, EV chargers, tenant sub-metering | Workshops, commercial stores, machine feeders | Industrial plants, PFC panels, bi-directional solar |
Frequently asked questions
What does a kWh meter measure?
A kWh meter totals and displays the electrical energy that a load or line consumes over a given time, in kilowatt-hours. It measures accumulated energy, not instantaneous power. In sub-meters, this value is used to separate and compare consumption by tenant, machine or panel.
What is the difference between a direct-connected meter and a current-transformer meter?
In a direct-connected meter, the measured current passes through the device's own terminals and is limited to the nominal current given by the manufacturer. In a current-transformer meter, the current transformer reduces the line current and the meter reads this secondary value. The choice is based on the line current, according to the project and the manufacturer data.
What is a meter with Modbus and BACnet output used for?
The communication output transfers the meter's energy values to energy monitoring software, a PLC or building automation. Modbus RTU runs over an RS-485 line; the iEM3155 manufacturer data states Modbus RTU and an RS485 screw terminal. BACnet is a protocol used in building automation systems; it is chosen according to the system's protocol.
What is a pulse output meter?
A pulse output meter generates one electrical pulse for each fixed amount of energy it measures. These pulses are counted in a PLC, counter or data logger and converted into consumption. It is a simple remote reading method without setting up a communication line; the energy per pulse is taken from the product data.
What do Class 1 and Class B mean on a meter?
These indicate the accuracy class of active energy measurement. The manufacturer data states Class 1 according to IEC 62053-21 and Class B according to EN 50470-3 for the iEM3155. Which class is required depends on the project and the requirements of the relevant authority; when comparing, look at values given according to the same standard.